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Components and Consequences of Cross-Laminated Timber Delamination

Conference paper

Abstract

Mass timber products such as cross-laminated timber are increasingly being used in tall timber building designs. The high-density wood used in mass timber products has a natural self-extinguishment capacity which chars only under exposure from an external heat flux. This makes timber a suitable building material giving timber buildings the potential to withstand full fire burnout of the building furnishings. However, ply delamination poses a significant challenge as the loss of the char layer exposes the unburnt wood and prevents the insulating char from regulating the heat flux to the unburnt wood. Even further, ply delamination means the structurally designed composite action of the mass timber product has been lost, and the ply could fall off into the compartment fire increasing the room fuel load. Ply delamination is extremely complex involving the resolution of heat transfer and structural equations as well as variables which are functions of temperature, moisture content, and many other factors. To date, the structural and thermal effects of cross-laminated timber delamination have not been comprehensively studied. This paper seeks to review the current research into delamination and highlight the research gaps that still exist. The current market focuses primarily on charring and eliminates the thermal penetration depth at the expense of losing understanding on a major failure mode of engineered timber. More detailed research into delamination is necessary to confidently ensure tall timber buildings meet the stakeholder’s goals of providing a safe building which can withstand complete fire burnout.

Keywords

Delamination Two-way spanning Mass timber products Thermal penetration depth Charring 

Nomenclature

A

Pre-exponential factor

c

Specific heat

k

Thermal conductivity

q

Heat flux

t

Time

x

Distance

E

Activation energy

M

Strength

R

Universal gas constant

T

Temperature

V

Strength reduction rate

ΔH

Heat of combustion

Greek Symbols

δ

Small surface thickness

ρ

Density

Subscripts

Ambient

tpd

Thermal penetration depth

vw

Virgin wood

Notes

Acknowledgment

The authors would like to thank The University of Queensland Civil Engineering Department Technical Staff for their help in the experimental studies conducted as part of the entire research project and the Queensland Department of Agriculture and Fisheries for manufacturing the CLT specimens used in the study.

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Copyright information

© Springer Science+Business Media Singapore 2017

Authors and Affiliations

  1. 1.School of Civil EngineeringThe University of QueenslandSt. LuciaAustralia

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